Picking up convenience store snacks is a habit that could cost more than $70,000 within a 20-year time period, according to Barbara Friedberg, a personal finance adviser.

“As a volunteer tax preparer for lower income folks, I was amazed at the frequency during which the clients came in with a convenience store snack; small pack of cheese crackers, a soda, a candy bar, or another quick item,” Freidberg wrote in her article. “In contrast, before my three hour shift, I packed a drink and snack for myself at home and brought it with me.”

A sweet roll from a convenience story could cost $2, coffee another $2, a pack of crackers and cheese $1.25 and soda $1.70; that adds up to $6.95.

If those same snacks are brought from home, a donut costs 75 cents, coffee 50 cents, crackers with cheese 75 cents and soda 25 cents, which is a total of $2.25.

Friedberg’s point is by eating the same snack at work brought from home rather than a convenience store, a person can save $4.70. When multiplied by each day of the year, that’s $1,715.50. If that money was invested rather than spent on pricey snacks, a mutual fund with seven percent return would make it $70,307 by the end of 20 years.

The problem with replacing convenience store habits is just that: convenience. Friedberg suggests taking a few hours one week to buy supplies and store them at work or in the car for when they're needed. Ultimately, it comes down to deciding if the convenience is worth thousands of dollars in the future.